Hi,
I am new to the forum and the openBVE program and I want to know how to decorate the exterior and interior of the train using bitmap images and csv's.

Well ... for the exterior, you can sometimes just modify or replace the existing images. In most cases, they are located in a subfolder named ext_view or something like that within the train's folder.

If you want to do anything more than that, you will need to do some studying. The train exteriors (and some new 3D cabs) are built the same way as other scenery objects such as buildings or trees.

Object building tutorials can be found at:
http://dennislance.zoomshare.com/1.html
http://bve.altervista.org/guide.html
http://www.bvestation.com/forums/index.php?board=81.0

More on the specifics of train exteriors:
http://openbve.trainsimcentral.co.uk/de ... s_cfg.html

Traditional 2D are mostly made in the same way as in the older program BVE4, so the following guide should be helpful:
http://www.roman-road.co.uk/temp/tutorial/

All openBVE commands for 2D cabs:
http://openbve.trainsimcentral.co.uk/develop/index.html

thank you very much

and i want to know how to decorate the front and the top of the train.